Endothelial cell parameters obtained in vivo using the clinical specular microscope will be compared to the in vitro histological assessment of the same corneas. The regular rabbit endothelial mosaic and the pleomorphic mosaic of the traumatized feline endothelium will be investigated for these parameters. The randomness of sampling by specular microscopy will be evaluated. Similar investigations will be instituted in animal corneas with localized and generalized endothelial trauma. The specular microscope will be used to document the in vivo human morphologic features of various endothelial disorder states, such as posterior polymorphous dystrophy, pigment dispersion, and mesodermal dysgenesis syndromes. Animal models of acute graft rejection and endothelial pigment interactions will be studied longitudinally by specular microscopy. Human, clinico-pathological correlations of endothelial diseases will be performed by comparing the in vivo specular microscopic appearance with the histological details after corneal removal by keratoplasty or enucleation.